This invention generally relates to the separation of the liquid phase from a mixture of liquids and solids, hereafter called a wet mixture. More particularly, this invention concerns an improved method and apparatus for expressing the liquid phase from a wet mixture that utilizes rolls biased against each other to yield a relatively dry mixture, hereinafter referred to as cake.
There are at present several methods by which the liquid and solid fractions or phases of a wet mixture can be separated to yield a cake. These include vacuum filtration, pressure filtration, centrifugation and compression in, for example, the so-called belt presses. Any of these methods will yield a cake that, although appearing dry, may still contain more than fifty percent moisture by weight. In situations where the cake must be further dewatered, removal of further liquid phase is typically carried out by heating, which of course significantly adds to the overall operating expense, especially in view of the current high energy costs. For these reasons, it is apparent an improved apparatus that would mechanically remove sufficient liquid phase from the wet mixture to avoid such additional steps would be desirable, not only from the viewpoint of managing the costs of the liquid-solid separation, but also from the broader perspective of conserving scarce energy resources.